Rotary cutting dies are widely used for manufacturing boxes, cartons, and interpak-die cuts. The rotary die includes a die cylinder and anvil cylinder mounted in parallel-spaced relation to one another. The cutting die includes a series of cutting rules for shaping a blank, and a series of creasing rules for producing fold lines in the blank where it is to be folded. The anvil cylinder is covered with a blanket of urethane or other resilient material. The cylinders rotate in opposite directions and the board is fed between the cylinders. The cutting die, in cooperation with the anvil cylinder, cuts out a blank from the sheet material and produces fold lines in the blank.
In operation, the size of the nip (the space between the cylinders) is adjusted depending on operating conditions. For example, the blanket surrounding the anvil will be relatively thick when new, but will wear over time. Wear on the blanket will therefore effect the size of the nip which in turn will effect the feed rate of the board passing between the die cylinder and the anvil cylinder. When the blanket is new, there is a tendency for the anvil to feed more board than is desired for each rotation of the anvil. To compensate for the excessive feed, the operator may move the cylinders closer together. Conversely, as the blanket wears, the amount of board fed between the cylinders will decrease. The operator will compensate for inadequate feed by moving the cylinders farther apart.
The adjustments made to compensate for the size of the blanket will also effect score quality. When the cylinders are moved closer together, the creasing rules may produce excessive scores or tend to cut the board. When the cylinders are moved further apart, the creasing rules will produce a light score.
The conditions of the paper will also effect the score quality. For example, when the board is dry, there is a tendency for the board to tear and a lighter score is needed. When the board is wet, it does not cut well and the operator will typically move the cylinders closer to improve the score quality.
In order to maintain a consistent score quality while making adjustments in the nip, it is sometimes necessary to replace the scoring rules with scoring rules of different heights. For example, when the cylinders are moved closer together and the size of the nip is reduced, a shorter scoring rule can be used to prevent excessive scoring and cutting of the board. Similarly, when the cylinders are moved further apart and the size of the nip is increased, a taller scoring rule is needed. Making such changes in the die requires die-makers tools, which are not always available to rotary die operators. Further, it takes a relatively large amount of time to replace scoring rules. This downtime significantly effects the productivity of the rotary die operation.
Accordingly, there is a need for a scoring rule in which the height of the rule can be adjusted relatively quickly by the rotary die operator.